Just a random idea that came to my mind when I accidentally came across that one pose linked below.

To clarify: this image is NOT intended to imply that Pinkie has, uh, bad hygiene habits. She's Pinkie Pie, remember? What if she can wander around and collect scents like they were, let's say, bottle caps?

She could come across a new scent, use her mystic Pinkie powers to capture its essence, and just wander away. Other than that, she would be pretty much fine with keeping herself clean, I believe. And you could feel those scents only if you were unlucky enough to have that tail pushed right into your face...

(26.08.2012) Updated into an actual vector. A few details were changed, like Twilight's expression, her body pose, and the length of their legs (they seemed a bit too short). Also, I increased the general thickness of the outlines to make it look more show-wise. Now it looks much better I believe.

I bet Pinkie's tail tastes like cotton candy. No wonder so many ponies (and one alligator) bite her tail. Although her tail has been bitten only once more than Rainbow Dash's tail which presumably tastes like skittles. Skittles: Taste the rainbow.

Tirek: Why couldn't I taste the rainbow the way Applejack and Pinkie Pie do, by biting Rainbow Dash's tail?Cerberus: It could be worse. You could've ended up like your G1 counterpart when HE tasted the rainbow.(Show scene of G1 Tirek being blasted apart by the rainbow and obliterated in a massive explosion of light)

This reminds me of The Hitchhikers Guide to the Galaxy. Where Hitchhikers would put things into and on there towels. Some hitchhikers would even dip parts of their towel in certain things so they had some source of food. Also, I wouldn't say the ponies that had that tail in their face were unlucky. But that may just be me XD